A new design of a parallel chord optical probe and its application to the plasma diagnostics

Summary form only given, as follows. A new optical probe system which is a dual function of linear and rotating motion is developed. It consists of an optical fiber, a small achromatic bi-convex lens and an optical vacuum feedthrough. The optical configuration of the system is carefully designed to have a parallel chord along the viewing direction. The optical line emission intensity from an ICP (inductively coupled plasma) is measured in axial and radial directions. The probe is moving along the axial direction, but it also can observe the radial direction because a 45 degree inclined mirror assembly can be attached to the probe head. The spatial intensity distribution in axial direction is obtained by a direct differentiation of the line integrated intensity, and the Abel inversion method is used to get the radial intensity distribution. The results are compared with those of Langmuir probe experiment to confirm the utilization of this probe system.